The present invention relates to integral fluid pumps and electric motors and integral fluid turbines and electrical generators. Throughout the specification these are defined as integral motor/generators and pump/turbines. More specifically, the present invention relates to hydrostatic servo positioning system and thrust bearings that stabilize the actual position of a rotor in a stator of an integral motor/generator and pump/turbine.
In my U.S. Pat. No. 5,209,650 entitled Integral Motor and Pump, I disclosed integral motors/generators and pump/turbines with a hydrostatic servo positioning system and hydrostatic thrust bearings. As disclosed in my previous patent, seal liquid is introduced through a fixed axial shaft to hydrostatic servo positioning system and thrust bearings and then exits through mechanical seals. The seal liquid is pressurized using centrifugal force caused by the rotor rotating within the stator casing. Because the unit is integral, external mechanical seals and stuffing boxes are not needed.
As internal mechanical seals are made more efficient, less seal liquid passes through them, thus there is less liquid available for the servo control of the positioning system and the hydrostatic thrust bearings. In my earlier patent, U.S. Pat. No. 5,209,650, all the seal liquid followed a series path which passed through the servo annular ring gap, through the thrust bearing chambers and through the internal seals on either side of the rotor. However, if the seal liquid flow is reduced, there is less liquid for the servo control of the hydrostatic thrust bearings, thus the servo annular ring gaps have to be reduced. The limit of reduction of the servo annular ring gaps is the tolerance of the axial bearing formed by the rotor and the fixed shaft, after which the rotor will contact the stator.
In order to overcome this problem, I have discovered that the seal flow liquid through the servo annular gaps can be increased by recirculating the seal liquid through the servo annular gaps. This increase flow through the servo annular gaps facilitates pressure attenuation of the seal liquid flow across the annular servo gap at larger gap spacings. Hence the servo system can operate at larger clearances and avoid contact between the stationary and rotating parts.
As in my previous patent, the servo mechanism varies the flow of seal liquid between two thrust bearings to take into account changes in axial thrust on one end of the rotor to stabilize the rotor within the stator.